Add map settings control (mock up).

This is not yet implemented but left visible for demo purposes.

Intended to configure things such as vessel track length, possibly
whether the latest track or the track within the current prospect
is shown, etc.

lib/www/client/source/src/views/Map.vue

@@ -122,6 +122,19 @@
         >
         </v-select>
         END QC data -->
+
+        <hr class="my-2"/>
+
+        <div title="Not yet implemented">
+          <v-btn
+            small
+            text
+            disabled
+          >
+            <v-icon small left>mdi-cog-outline</v-icon>
+            Map settings
+          </v-btn>
+        </div>
       </div>
     </div>